Diastolic heart failure (DHF) is a form of heart failure that occurs when ventricular filling is impaired during the diastolic phase of the cardiac cycle. An estimated fifty percent or more of all heart failure patients may suffer from diastolic heart failure. Patients with DHF may experience symptoms related to congestive heart failure, including reduced exercise capacity and impaired quality of life. Impaired ventricular filling can be caused by ventricular hypertrophy, which increases the stiffness of the ventricular chamber. Ejection fraction may be preserved in patients with diastolic heart failure, which is sometimes referred to as heart failure with preserved ejection fraction or HFpEF. Patients suffering from systolic heart failure typically experience a worsening ejection fraction as the heart muscle becomes less effective at pumping or ejecting blood. Patients suffering from systolic heart failure may have impaired diastolic function as well.
Cardiac resynchronization therapy (CRT) is a cardiac stimulation therapy administered to patients having systolic HF. Impaired ejection during cardiac systole can be caused by dyssynchrony of the right and left ventricular chambers. When proper ventricular synchrony is restored, by pacing either one or both ventricular chambers, an improvement in ejection fraction is possible. A need remains, however, for treating impaired diastolic filling in patients experiencing DHF.